Neural Systems, Inhibitory Control, and Methamphetamine Dependence

The Neural Systems, Inhibitory Control, and Methamphetamine Dependence study started in 2011 and is currently finishing data collection for its last participants. The study included methamphetamine abusing individuals and healthy control participants aged 18-55 years. Participants who qualified over the telephone were scheduled to visit the London Laboratory at the UCLA Semel Institute for Neuroscience and Human Behavior for the In-Person Screening Phase. The screening procedures, usually scheduled over two visits, determined if participants were eligible to complete the subsequent study visits. Both groups completed identical screening procedures, with the exception of more in-depth drug use questions for the methamphetamine users. After providing written consent, participants completed questionnaires about their mood, medical, psychiatric and drug use history, personality and life experiences. They also provided a urine sample to determine what drugs they recently used and a breath sample to determine the carbon monoxide levels in their system. The drug screen tested for recent methamphetamine, cocaine, opiates/opioids, benzodiazepines, THC and other amphetamines. Methamphetamine participants needed to test positive for methamphetamine at admission. If methamphetamine participants tested positive for any drugs other than methamphetamine or marijuana, and if healthy control participants tested positive for any drugs other than marijuana, they were excluded from the study. Additionally, the urine samples of female participants were tested for pregnancy; pregnant females were also excluded. If no exclusionary criteria were met during the first screening visit, participants completed a second screening visit to ensure they were mentally and physically healthy enough to participate. The second screening visit included a psychiatric diagnostic interview (DSM-IV (SCID-I) for first 500 participants and the MINI International Neuropsychiatric Interview M.I.N.I for the last 50 participants). Additionally, laboratory tests and procedures were completed by the UCLA General Clinical Research Center and interpreted by a study physician. Laboratory tests included vital signs (heart rate--BPM, blood pressure, and respirations), an electrocardiogram (ECG) to record the electrical activity of the heart, and an 18-cc blood sample to perform laboratory tests which included a complete chemistry and metabolic panel, hepatic panel, Hepatitis-C tests, and HIV test. The laboratory tests from this blood sample ensured that participants' liver and kidneys were functioning normally, and that their standard blood counts (red cell, white cell, and salts) were also normal. If a Hepatitis-C (HCV) or HIV test was positive, participants were not allowed to continue in the study and their results were reported to the California State Health Department. Participants deemed eligible to continue in the methamphetamine group participated on an outpatient basis or were admitted to the UCLA Medical Center to participate on an inpatient basis for up to 10 days. Typically, detectable levels of methamphetamine in urinalysis remain for 2-3 days, therefore inpatient days 0-3 served as a "washout period" and the methamphetamine abusing inpatient participants provided daily urine samples to test for recent drug use and pregnancy (female participants only). Outpatient participants were also required to remain abstinent from all drugs except nicotine and marijuana for at least 4 days prior to study sessions. Self-reported abstinence for outpatients was verified by urine toxicology and saliva screening at every visit to UCLA before completion of study procedures. Neurocognitive assessments, about three hours each, typically took place on two separate days. The purpose of the neurocognitive sessions were to assess participants' intellectual and neurocognitive functioning. On either the same day as the neurocognitive testing or on separate days, both methamphetamine abusers and healthy controls were administered a structural MRI to collect information on brain structure.]]>
Participants (18-55 years of age) completed a screening visit to ensure that they met criteria for mental and physical health. A physical examination and lab tests were done. The Structured Clinical Inventory for DSM-IV (SCID-I) was used to determine psychiatric diagnoses for the first 500 participants. The MINI International Neuropsychiatric Interview M.I.N.I was used to determine psychiatric diagnoses for the last 50 participants. Exclusion Criteria: Psychiatric Disease: Current diagnosis of an Axis I disorder (according to DSM-IV criteria), except for the following: Current Stimulant (Meth) Dependence or Abuse (Meth group only) Current Marijuana Dependence or Abuse (both groups) Current Nicotine Dependence (both groups) Current Mood Disorder due to substance use Current Anxiety Disorder due to substance use Drug Use History-Meth abusers must: Meet DSM-IV criteria for current Meth Dependence or Abuse Test positive on day of screening for Meth by urine sample Medications and Substances-Evidence of current use of psychotropic medications or substances other than: Light use of marijuana (both groups) Light use of alcohol (both groups) Nicotine Note: "Light use" defined by qualification for abuse but not dependence. Tobacco (cigarette) consumption is matched between groups to equalize possibly confounding effects of nicotine on cerebral blood flow, which may affect hemodynamic changes measured by fMRI. CNS Disease-Including: Structural brain abnormalities (e.g., neoplasms, subarachnoid cysts) Cerebrovascular disease Infectious disease (e.g., abscess) History of other neurological disease, including stroke or head trauma (defined as loss of consciousness >30 min or requiring hospitalization) Cardiovascular Disease: Advanced coronary artery disease, endocarditis, or other cardia disease likely to result in cerebral embolism Any participant that exhibits evidence of left ventricular hypertrophy will be evaluated for a history of hypertension, and will be excluded from participation if positive for hypertension Any participant that reports cardiac symptoms such as chest pain, presyncope and/or syncope with meth use Pulmonary Disease: Significant obstructive pulmonary disease Self-reported active tuberculosis Systemic Disease: Endocrinopathies Renal or hepatic failure Autoimmune disease involving the CNS Pregnancy: Pregnancy, possible pregnancy, or failure to indicate the use of reliable birth control precautions. Note: We administered a pregnancy test to each female participant before starting each of the testing days. Participants must agree to use an effective form of birth control throughout the study. The only acceptable methods of birth control are: 1) oral contraceptive; 2) Depo-Provera injection; 3) intrauterine device; 4) diaphragm with contraceptive jelly; 5) condom with contraceptive jelly, foam, or sponge; 6) tubal ligation or hysterectomy; 7) abstinence from heterosexual intercourse. HIV: HIV-seropositive will be excluded because HIV infection and the development of AIDS produce alterations in brain activity that are dependent on the stage of AIDS. Such effects on brain activity would confound the results of this study. Severe Hepatic Impairment: Participants who have severe hepatic impairment, as assessed by blood tests and/or medical history, will be excluded from participation in order to reduce the risk of an adverse effect due to the administration of medication. Only for MRI Procedures: We excluded any participant whose body contains a ferromagnetic implanted device that might produce a safety hazard during fMRI. We followed guidelines found in the manual, Magnetic Resonance: Bioeffects, Safety, and Patient Management, supplemented by the current information published on the International MR Safety Website: http://www.mrisafety.com/safety_info.asp Language: Lack of fluency in English. If a participant is not a fluent English speaker, the language barrier would interfere with performance of psychological tests and completing questionnaires used in the study. The consent form, all questionnaires and instructions are given in English. Neurological: Neurological status that is not within normal limits as determined by a physician and as indicated in self-reports. Radiation Exposure: Participated in any other research study involving exposure to ionizing radiation in the past year, relating to study visit date, if the total cumulative exposure from the past research studies and the current research study exceeded the limits described by the FDA in 21 CFR 361.1. Specifically, the total cumulated dose to the whole body, active blood-forming organs, lens of the eye, and gonads must have remained below 5 rems, and the cumulated dose to all other organs must have remained below 15 rems. Radiation Exposure: Participated in any other research study involving exposure to ionizing radiation in the past year, relating to study visit date, if the total cumulative exposure from the past research studies and the current research study exceeded the limits described by the FDA in 21 CFR 361.1. Specifically, the total cumulated dose to the whole body, active blood-forming organs, lens of the eye, and gonads must have remained below 5 rems, and the cumulated dose to all other organs must have remained below 15 rems. ]]>